Cutting device for thin semiconductor wafer and cutting method thereof

Abstract

A cutting device for a thin semiconductor wafer includes a laser light generator and a polygonal mirror structure. The laser light generator is used to provide a femtosecond laser light with a pulse width on a femtosecond order (10−15 second). The polygonal mirror structure is used to reflect the femtosecond laser light. The polygonal mirror structure has a plurality of reflective surfaces. The polygonal mirror structure rotates continuously with respect to the femtosecond laser light, such that the femtosecond laser light is sequentially and repeatedly reflected by the plurality of reflective surfaces and projected on a semiconductor wafer. The femtosecond laser light projected on a semiconductor wafer moves repeatedly along a same predetermined direction in a predetermined range during a predetermined time to groove or cut the semiconductor wafer.

What is claimed is: 
     
       1. A cutting device for a thin semiconductor wafer, comprising:
 a laser light generator configured to provide a femtosecond laser light with a pulse width on a femtosecond order; 
 a polygonal mirror structure having a plurality of reflective surfaces and configured to
 reflect the femtosecond laser light; and 
 rotate continuously with respect to the femtosecond laser light, such that the femtosecond laser light is sequentially and repeatedly reflected by the plurality of reflective surfaces and projected on a semiconductor wafer, and moves repeatedly along a same predetermined direction in a predetermined range during a predetermined time to cut the semiconductor wafer; and 
 
 a position detection module including a detecting light emitter, a reflective mirror and a detecting light receiver; 
 wherein, after a detecting light provided by the detecting light emitter is sequentially reflected by one of the reflective surfaces of the polygonal mirror structure and the reflective mirror, the detecting light receiver is configured to receive the detection light and detect an initial position of a rotation of the polygonal mirror structure according to the detecting light; 
 wherein, when the femtosecond laser light is provided by the laser light generator and the detecting light is provided by the detecting light emitter, a transmitting path of the detecting light transmitted from the position detection module to the detecting light receiver does not overlap with a transmitting path of the femtosecond laser light transmitted from the laser light generator to the semiconductor wafer. 
 
     
     
       2. The cutting device according to  claim 1 , further comprising an optical correction module including an X-axis galvanometer and a Y-axis galvanometer, wherein the femtosecond laser light is adjusted by the X-axis galvanometer and the Y-axis galvanometer so as to be projected within the predetermined range. 
     
     
       3. The cutting device according to  claim 1 , further comprising a laser beam expander configured to adjust a diameter of the femtosecond laser light provided by the laser light generator. 
     
     
       4. The cutting device according to  claim 1 , wherein a thickness of the semiconductor wafer is less than 100 μm. 
     
     
       5. The cutting device according to  claim 1 , further comprising: an air suction assembly disposed above the semiconductor wafer and a blowing assembly disposed above the semiconductor wafer, wherein the air suction assembly sucks in air so that dust generated by the laser cutting on the semiconductor wafer is introduced into the air suction assembly, and the blowing assembly blows air toward the dust generated by the laser cutting, so that the dust is blown in the direction toward the air suction assembly. 
     
     
       6. A cutting method for a thin semiconductor wafer, comprising:
 providing a semiconductor wafer; 
 providing, by a laser light generator, a femtosecond laser light with a pulse width on a femtosecond order; and 
 providing a polygonal mirror structure having a plurality of reflective surfaces, wherein the femtosecond laser light is reflected by the polygonal mirror structure, 
 wherein the polygonal mirror structure rotates continuously with respect to the femtosecond laser light, such that the femtosecond laser light is sequentially and repeatedly reflected by the plurality of reflective surfaces and projected on the semiconductor wafer, and moves repeatedly along a same predetermined direction within a predetermined range and within a predetermined time to cut the semiconductor wafer; 
 wherein the cutting method further comprises:
 providing, by a detecting light emitter, a detecting light; 
 reflecting, sequentially by one of the reflective surfaces of the polygonal mirror structure and a reflective mirror, the detecting light; and 
 receiving, by a detecting light receiver, the detecting light to detect an initial position of a rotation of the polygonal mirror structure according to the detecting light; 
 
 wherein a transmitting path of the detecting light transmitted from the position detection module to the detecting light receiver does not overlap with a transmitting path of the femtosecond laser light transmitted from the laser light generator to the semiconductor wafer. 
 
     
     
       7. The cutting method according to  claim 6 , further comprising:
 adjusting, by an X-axis galvanometer and a Y-axis galvanometer of an optical correction module, the femtosecond laser light so that the femtosecond laser light is projected within the predetermined range. 
 
     
     
       8. The cutting method according to  claim 6 , further comprising:
 adjusting, by a laser beam expander, a diameter of the femtosecond laser light provided by the laser light generator. 
 
     
     
       9. The cutting method according to  claim 6 , wherein a thickness of the semiconductor wafer is less than 100 μm.